A multi-ion detection Schiff base chemosensor: turn-off and ratiometric fluorescence sensing of Ni2+, Co2+, Cd2+, and Cu2+ions

Bhavya, N. R. and Madegowda, M. and Neelufar and Ananda, S. and Javarappa, R. and Nagaraja, N. (2025) A multi-ion detection Schiff base chemosensor: turn-off and ratiometric fluorescence sensing of Ni2+, Co2+, Cd2+, and Cu2+ions. Journal of Molecular Structure, 1337. ISSN 0022-2860

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Official URL: https://doi.org/10.1016/j.molstruc.2025.142183

Abstract

A novel Schiff-based fluorescent sensor, (Z)-2-((1H-indol-3-yl)methylene)-N'-((Z)-(1H-indol-3-yl)methylene)hydrazine-1-carbothiohydrazide (NF16) for multi-ion sensing was designed and synthesized to detect Ni2+, Co2+, Cd2+, and Cu2+ ions in DMSO and water systems. The fluorophore detects the metal ions through fluorescence turn-off and ratiometric sensing facilitated by chelation-enhanced quenching and intramolecular charge transfer mechanisms. The sensor NF16 exhibited relatively low detection limits of 2.363 x 10-6, 4.1 x 10-5, 2.040 x 10-6, and 1.649 x 10-6 M for Cu2+, Cd2+, Ni2+,and Co2+, respectively. The binding constants for the NF16-metal complexes were 4.112 x 105, 8.383 x 103, 5.123 x 103, and 8.398 x 103 M-1, respectively, for NF16-Cu2+, NF16-Cd2+, NF16-Ni2+, and NF16-Co2+complexes. The mass spectra and Job's plot analysis confirmed a 2:1 (NF16: metal ion) stoichiometric binding ratio between NF16 and the metal ions. All the experimental outcomes strongly propose that NF16 is a highly effective sensor for Cu2+, Cd2+, Ni2+, and Co2+. In the metal ion interference studies, it is observed that the detection of Cu2+ ions is not affected by the presence of other metal ions, including Cd2+, Ni2+, and Co2+ ions, indicating that NF16 has more selectivity towards Cu2+ ions, and it could be a possible candidate for Cu2+ ion sensing applications.

Item Type: Article
Uncontrolled Keywords: Schiff base, Multi-ion sensing, Ratiometric sensor, Turn-off, Limit of detection, TD-DFT,
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: Ms Varalakshmi
Date Deposited: 03 Nov 2025 10:42
Last Modified: 03 Nov 2025 10:42
URI: http://eprints.uni-mysore.ac.in/id/eprint/17900

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